Symmetry is the cornerstone of modern physics. It is a concept that is familiar to many. The Canadian Oxford
Dictionary defines it as a ``correct proportion of the parts of a thing, balance, harmony'' and ``beauty resulting from this''.
Clearly symmetry and beauty seem to be naturally connected. This connection between symmetry and beauty is also present in Physics. Theories with the greatest amount of symmetry are considered to be the most beautiful or desirable. In fact, as I will argue towards the end, aesthetics based
on symmetry seems to be taking an increasingly (and perhaps disproportionately) important role in
determining the course of modern physics.

The first thing that I need to do is
to give you a theorist's view of what Physics is about, and what I consider beautiful
about it (``Why I didn't hate Physics in High School''). Next I will tell you what
Symmetry means to a physicist and how it is used. In the last part of the talk I will
focus on one particular puzzle in theoretical physics (``black hole evaporation'') which
to my mind highlights all the key points of what I am trying to convey. It is of course no coincidence that this puzzle is one of the subjects of my current research.